Vowelized Consonants-2

>So i tried that with another consonant, namely /k/.
>It sounds like each jaw-form has it's own default vowel:
>
>normal /k/ sounds like /k@/
>grinning /k/ sounds like /kI/
>lips-rounded /k/ sounds like /ku/
>jaw-dropped /k/ sounds like /ka/
>
>Is this a known phonological fact, or am i just imagining it?

JimG -- I work as a speech therapist.   Your observation sounds more
phonetic than phonological to me.    Try grinning and dropping your jaw at
the same time.    If you find this difficult, you might consider the
possibility that you're affecting vowel height through the degree of jaw
excursion:   lower jaw, lower vowel.   For those who came in late, [I] is
high, and [@] is central.

>And does anyone know how in IPA to mark these kinds of consonants,
>specifically the grin-hissing /s/ ?

JimG -- Hmmm.   Dunno.